The Application of Tomato Plant Residue Compost and Plant Growth-Promoting Rhizobacteria Improves Soil Quality and Enhances the Ginger Field Soil Bacterial Community

Treating and utilizing vegetable residues may reduce waste and improve rhizosphere soil. This study explored the effects of tomato plant residue compost and plant growth-promoting rhizobacteria (PGPR) on the physicochemical properties and microbial community of ginger field soil. Four treatment procedures were adopted: no compost or PGPR (CK), compost (TC), compost + Bacillus subtilis (TC-BS), and compost +Bacillus amyloliquefaciens SQR9 (TC-BA). The results showed that compared with the CK, TC significantly increased soil organic matter, alkali hydrolyzable nitrogen, available phosphorus, and available potassium by 17.34%, 21.66%, 19.56%, and 37.20%, respectively. Soil urease activity, neutral phosphatase activity, and sucrase activity increased by 55.89%, 35.59%, and 57.21%, respectively. Chloroflexi, Gemmatimonadetes, and Bacillus abundances increased by 1.40%, 1.80%, and 0.68%, respectively, while Firmicutes decreased by 0.80%. TC-BS significantly improved soil bacterial diversity than CK and TC, and relative abundance of Beneficial Proteobacteria, Acidobacteria, Chloroflexi, and Bacillus microorganisms dominated. Principal coordinate analysis revealed significant differences in bacterial community structure among different treatments. Redundancy analysis indicated total potassium (p = 0.002), pH (p = 0.0012), and available phosphorus (p = 0.016) as the main community composition driving factors. In conclusion, B. subtilis inoculation in ginger field soil supplemented with tomato compost enhanced bacterial diversity, altered bacterial community structure, enriched beneficial microorganisms, and promoted a healthy rhizosphere.